Lubricant additives



hired 2,929,828 LUBRICANT ADDITIVES Application September 28, 1955' Serial No. 537,278

Claims. (Cl. 260-448) No Drawing.

This invention relates to lubricants and more particularly relates to a new class of products useful as lubricant additives. Still more particularly the invention relates to reaction products of aluminum alcoholates with phosphosulfurized hydrocarbons, to methods for preparing these reaction products, and to lubricant compositions containing these products as additives.

The utilization of additives in lubricating oil compositions is well known. These additives are used to improve one or more characteristics of the lubricating oil compositions such as viscosity index, pour point, oxidation resistance, corrosion resistance, detergency, and the like, and are employed extensively in lubricating oil compositions for internal combustion engines such as automotive and aviation engines. Due to the increasing severity of engine operation, there is a continuing and critical need for new and improved additives which are capable of imparting improved characteristics to the lubricating oil compositions. Preferably, such new additives will improve more than one characteristic or property of the oil.

It has now been found that reaction products of aluminum alcoholates with phosphosulfurized hydrocarbons are outstanding lubricant additives. More particularly, these reaction products have been found to be particularly effective detergents and inhibitors for lubricating oil compositions, particularly in mineral lubricating oil compositions, used in internal combustion engines. In addition to these outstanding properties, the present reaction products have reduced tendency to evolve hydrogen sulfide upon storage and use.

The hydrocarbon materials which may be reacted with a phosphorus sulfide in the first step of the production of additives of the present invention may be paraflins, olefins or olefin polymers, diolefins, acetylenes, aromatics or alkyl aromatics, cyclic aliphatics, petroleum fractions, such as lubricating oil fractions, petrolatums, waxes, cracked cycle stocks, or condensation products of petroleum fractions, solvent extracts of petroleum fractions, etc.

Hydrocarbons such as bright stock residuums, lubricating oil distillates, petrolatums or paraflin waxes may be employed. There may also be employed products obtained by condensing any of the foregoing hydrocarbons, usually through first halogenating the hydrocarbon, with aromatic hydrocarbons in the presence of anhydrous inorganic halides, such as aluminum chloride, zinc chloride, boron fluoride, and the like.

As examples of monoolefins may be mentioned isobutylene, decene, dodecene, cetene (C octadecene (C cerotene (C melene 30), olefinic extracts from gasoline or gasoline itself, cracked cycle stocks and polymers thereof, resin oils from crude oil, hydrocarbon coal resins, cracked waxes, dehydrohalogenated chlorinated waxes, and any mixed high molecular weight alkenes obtained by cracking petroleum oils. A preferred class of olefins are those having at least 20 carbon Patent cc 299299828 Patented Mar. 22, 1960 atoms per molecule, of which from about 12 to about 18 carbon atoms, and preferably at least 15 carbon atoms, are in a long chain. Such olefins may be obtained by the dehydrogenation of p'araifin waxes, by the dehydrohalogenation of long chain alkyl halides, by the synthesis of hydrocarbons from C0 and H by the dehydration of alcohols, etc.

Another class of suitable olefinic materials are the monoolefin polymers, in which the molecular weight ranges from to 50,000, preferably from about 250 to about 10,000. These polymers may be obtained by the polymerization of low molecular weight monoolefinic hydrocarbons, such as ethylene, propylene, butylene, isobutylene, normal and isoamylenes, or hexenes, or by the copolymerization of any combination of the above monoolefinic materials. 1

Diolefins which may be employed include well known materials such as butadiene, isoprene, chloroprene, cyclopentadiene, 2,3-dimethylbutadiene, pentadiene-1,3, hexadiene-2,4, terpenes and the like. Acetylene and substituted acetylenes may similarly be employed.

Another class of unsaturated hydrocarbon materials which may be advantageously employed in the preparation of the additives of this invention are high molecular weight copolymers of low molecular weight monoolefins and diolefins. The copolymer is prepared by controlled copolymerization of a low molecular weight olefin and a non-aromatic hydrocarbon showing the general formula C I-l in which x is 2 or a multiple of 2, in the presence of a catalyst of the Friedel-Crafts or peroxide type. The low molecular weight olefin is preferably an isoolefin or a tertiary base olefin preferably one having less than 7 carbon atoms per molecule. Examples of such olefins are isobutylene, Z-methylbutene-1,2-ethylbutene- 1, secondary and tertiary base amyiene, hexylenes, and the like. Examples of the non-aromatic hydrocarbons of the above formula which can be used are the conjugated diolefins listed in the preceding paragraph, diolefins such as 1,4-hexadiene, in which the double bond is not conjugated, as well as the acetylenes. The copolymerization is preferably carried out in the presence of aluminum chloride, boron fluoride, or benzoyl peroxide, and the copolymer is preferably one having a molecular weight of about 1,000 to 30,000.

Another class of hydrocarbons which may be employed in a similar manner are aromatic hydrocarbons, such as benzene, naphthalene, anthracene, toluene, xylene, diphenyl, and the like, including aromatic hydrocarbons having alkyl substituents and aliphatic hydrocarbons having aryl substituents.

A still further classof hydrocarbons which may be employed in the reaction with sulfides of phosphorus are condensation products of halogenated aliphatic hydrocarbons with an aromatic compound, produced by condensation in the presence of aluminum chloride or other Friedel-Crafts type catalyst. The halogenated aliphatic hydrocarbon is preferably a halogenated long chain paraffin hydrocarbon having more than 8 carbon atoms, such as paraflin wax, petrolatum, ozocerite wax, etc. High viscosity paraffin oils, particularly heavy residual oil which has been treated with chemicals or extracted with propane or other solvents for the removal of asphalts, may be employed. The aromatic constituent may be naphthalene, fiuorene, phcnanthrene, anthracene, coal tar residues, and the like.

Another type of hydrocarbon material which may be similarly employed is a resin-like oil which has a molecular weight of from about 1,000 to 2,000 or higher, obtained preferably from a paraflinic oil which has been dewaxed and which is then treated with a liquefied normally gaseous hydrocarbon, e.g., propane, to precipitate.

a heavy propane-insoluble fraction. The latter is a substantially wax-free and asphalt-free product having a Saybolt viscosity at 210 F. of about 1,000 to about 4,000 seconds or more. g The preferred hydrocarbon materials of this invent on are isobutylene polymers and refined mineral lubr cating oil bright stocks. The polyisabutylenes useful in this invention have molecular weights in the range of about 100 to 50,000, preferably about 250 to 10,000 and more preferably about 500 to 2,000. The refined mineral lubricating oil bright stocks are preferably those which have been deasphalted, solvent extracted or acid treated, dewaxed and filtered, having SSU viscosities at 210 F. in the range of about 100 to 200, preferably about 130 to 170. The phosphorus sulfide-hydrocarbon reaction product may be readily obtained by reacting a phosphorus sulfide, e.g., P P 8 P 8 P 8 or other phosphorus sulfide, preferably P 8 with the hydrocarbon at a temperature of about 200 F. to about 600 F., and preferably from about 300 F. to about 550 F., using from about 1 to about 10, preferably about 2 to about 5, molecular proportions of hydrocarbon to 1 molecular proportion of the sulfide of phosphorus in the reaction. It is advantageous to maintain a non-oxidizing atmosphere, such as an atmosphere of nitrogen, above the reaction mixture. Usually it is desirable to use an amount of the phosphorus sulfide that will completely react with the hydrocarbon so that no further purification becomes necessary. In the case of monoolefin polymers the preferred ratio is one molecular proportion of the sulfide of phosphorus to two to five molecular proportions of polymer. In such case the reaction is continued until all or substantially all of the phosphorus sulfide has reacted. The reaction time is not critical, and the time required to cause the maximum amount of phosphorus sulfide to react will vary greatly with the temperature. A reaction time of 2 to 10 hours is frequently necessary. If desired, the reaction product may be further treated by blowing with steam; alcohol, ammonia, or an amine at an elevated temperature of about 200 F. to about 600 F. to improve the odor thereof. The phosphosulfurized hydrocarbons will generally contain at least 1.0%, usually at least 2.0%, by weight of chemically combined sulfur. The phosphosulfurized hydrocarbons prepared as do scribed above are believed to be predominantly dihydrocarbon phosphinodithioic acids having the formula P R \SH where R and R are each derived from a molecule of the hydrocarbon. Thus, in general, the proportions of hydrocarbon and phosphorus sulfide will be selected to form a product derived from about 2 molecules of the hydrocarbon and containing 1 phosphorus atom.

In accordance with the present invention, the phosphosulfurized hydrocarbons are reacted with an aluminum alcoholate having the formula Al(OR) and more'particularly the formula alcoholates useful in the present invention are aluminum methylate, aluminum ethylate, aluminum propylate, aluminum amylate, aluminum octylate, aluminum dodecylate, aluminum octadecylate. aluminum dipropyl-monoamylate. These aluminum alcoholates useful in the present invention are prepared by well-known methods. For example, they may be prepared by direct action of alcohols on metallic aluminum in the presence of mercury or mercury compounds. Where the reaction is too vigorous, it is moderated by mixing the alcohol with a light petroleum fraction such as petroleum ether.

The reaction between the aluminum alcoholate and the phosphosulfurized hydrocarbon is carried out utilizing about 1 to 2 moles of the phosphosulfurized hydrocarbon per mole of aluminum alcoholate, preferably using approximately equimolar proportions of the phosphosulfurized hydrocarbon and aluminum alcoholate. Generally reaction temperatures in the range of about to 450 may be used. Preferred reaction temperatures are in the range of about 200 to 350 F. A reaction temperature of about 275 to 325 F. is particularly preferred. The reaction may be carried out for a period of time of about 0.2 to 10 hours, preferably about 2 to 6 hours. A reaction time of about 3 to 5 hours is particularly preferred. The reaction may be very effectively carried out utilizing a solvent such as, for example, a mineral lubricating oil. When a solvent is employed, it is preferred to employ the solvent in proportions to form a composition containing about 25% to 75% active ingredient (the reaction product of the aluminum alcoholate with the phosphosulfurized hydrocarbon). If desired, the by-product alcohol formed in the reaction may be removed from the reaction mixture by any one of a number of methods such as blowing with an inert gas, preferably at an elevated temperature, e.g., 150 to 450 F., or distillation under vacuum.

It is believed that the oxygen-containing reaction prod uct formed in accordance with the present invention is predominantly one or both of the following compounds:

where R, R R and R have their aforementioned definitions. The particular proportions of these two types of products in the final reaction products will depend upon the molar proportions of reactants employed. More specifically, the formation of the first-listed compound will be favored by the use of equimolar proportions of phosphosulfurized hydrocarbon and aluminum alcoholate whereas the second-listed compound will be favored by using about 2 moles of the phosphosulfurized hydrocar' bon per mole of aluminum alcoholate.

When additives of the present invention are employed in lubricating oils, they are preferably added in proportions of about 0.01 to about 20.0% or more, preferably about 0.5 to 10.0%, and more preferably about 1.0 to 6.0% by weight. ,The proportions giving the best results will vary somewhat according to the nature of the additive, the nature of the lubricating oil base stock to which it is added and the specific purpose which the lubricant is to serve in a given case. For commercial purposes, 'it is'convenient to prepare concentrated oil solutionsin' whichthe amount of additivein the composition ranges from to 50% by weight, and to transport and store them in such form. In preparing a lubricating oil composition for use as a crankcase lubricant the additive concentrate is merely blended with the base oil in the required amount.

The products of the present invention may be employed not only in ordinary hydrocarbon lubricating oils but also in the heavy duty type of lubricating oils which have been compounded with such detergent type additives as metal soaps, metal petroleum sulfonates, metal phenates, metal alcoholates, metal alkyl phenol sulfides, metal organo phosphates, thiophosphates, phosphites and thiophosphites, metal salicylates, metal Xanthates and thioxanthates, metal thiocarbamates, amines and amine derivatives, reaction products of metal phenates and sulfur, reaction products of metal phenates and phosphorus sulfides, metal phenol sulfonates and the like. Thus the additives of the present invention may be used in lubricating oils containing such other addition agents as barium tert.-octyl-phenol sulfide, calcium tert.-amylphenol sulfide, nickel oleate, barium octadecylate, ca cium phenyl stearate, zinc diisopropyl salicylate, aluminum naphthenate, calcium cetyl phosphate, barium di-tert.- amylphenol sulfide, calcium petroleum sulfonate, zinc methylcyclohexyl thiophosphate, calcium dichlorostearate, etc. Other types of additivcs such as phenols and phenol sulfides may be employed.

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paraffinic, naphthenic, asphaltic, or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced, for example, by solvent extraction with solvents of the type of phenol, sulfur dioxide, furfural, dichlorodiethyl ether, nitrobenzene, crotonaldehyde, etc. Hydrogenated oils, white oils, or shale oil may be employed as well as synthetic oils, such as esters and polyethers as well as those prepared, for example, by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. Also, for special applications, animal, vegetable or fish oils or their hydrogenated or voltolized products may be employed in admixture with mineral oils.

Synthetic lubricating oils may also be employed which have a viscosity of at least SSU at 100 F. such as esters of monobasic acids (e.g., ester of C Oxo alcohol with C Oxo acid, ester of C Oxo alcohol with octanoic acid, etc.), esters of dibasic acids (e.g., di-2- ethyl hexyl sebacate, di-nonyl adipate, etc.), esters of glycols (e.g. C Oxo acid diester of tetraethylene glycol, etc.), complex esters (e.g. the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2ethyl-hexanoic acid, complex ester formed by reacting one mole of tetraethylene glycol with two moles of sebacic acid and two moles of 2-ethyl hexanol, complex ester formed by reacting together one mole of azelaic acid, one mole of tetraethylene glycol, one mole of C Oxo alcohol, and one mole of C Oxo acid), esters of phosphoric acid (e.g. the ester formed by contacting three moles of the mono methyl ether of ethylene glycol with one mole of phosphorus oxychloride, etc.), halocarbon oils (e.g. the polymer of chlorotrifiuoroethylene containing twelve recurring units of chlorotrifiuoroethylene), alkyl silicates (e.g. methyl polysiloxanes, ethyl polysiloxanes, methyl-phenyl polysiloxanes, ethyl-phenyl polysiloxanes, etc.), sulfite esters (e.g. ester formed by reacting one 'mole of sulfur oxychloride with two moles of the methyl ether of ethylene glycol, etc.), carbonates (e.g. the carbonate formed by reacting C Oxo alcohol with ethyl carbonate to form a half ester and reacting this half ester with tetraethylene glycol), mercaptals (e.g. the mercaptal formed by reacting Z-ethyl hexyl mercaptan with formaldehyde), formals (e.g. the formal formed by reacting C 0x0 alcohol with formaldehyde), polyglycol type synthetic oils (e.g. the compound formed by condensing butyl alcohol with fourteen units of propylene oxide, etc.), or mixtures of any of the above (or with mineral oils) in any proportions may also be used.

For the best results the base stock chosen should normally be that oil which without the new additive present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils or other oils, no strict rule can be laid down for the choice of the base stock. Certain essentials must of course be observed.

The oil must possess the viscosity and volatility characteristics known to be required for the service contemplated. The oil must be a satisfactory solvent for the additive, although in some cases auxiliary solvent agents may be used. The lubricating oils, however they may have been produced, may vary considerably in viscosity and other properties depending upon the particular use for which they are desired, but they usually range from about 40 to 150 seconds Saybolt viscosity at 210 F. For the lubricating of certain low and medium speed diesel engines the general practice has often been to use a lubricating oil base stock prepared from naphthenic or aromatic crudes and having a Saybolt viscosity at 210 F. of 45 to seconds and a viscosity index of O to 50. However, in certain types of diesel engine and other gasoline engine service, oils of higher viscosfty index are often preferred, for example, up to 75 to 100, or even higher, viscosity index,

In addition to the material-to be added according to the present invention, other agents may also be used such as dyes, pour depressors, heat thickened fatty oils, sulfurized fatty oils, organo-metallic compounds, metallic or other soaps, sludge dispersers, anti-oxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, voltolized fats, voltolized mineral oils, and/or voltolized waxes and colloidal solids such as graphite or zinc oxide, etc. Solvents and assisting agents, such as esters, ketones, alcohols, aldehydes, halogenated or nitrated compounds, and the like may also be employed.

In addition to being employed in lubricants, the additives of the present invention may also be used in motor fuels, hydraulic fluids, torque converter fluids, cutting oils, flushing oils, turbine oils or transformer oils industrial oils, process oils and generally as detergents and inhibitors in mineral oil products. They may also be used in gear lubricants and greases.

The invention will be more fully understood by reference to the following examples. It is pointed out, however, that the examples are given for the purpose of illustration only and are not to be construed as limiting the scope of the present invention in any way.

Example I.-Preparati0n of reaction product of aluminum amylate with P S' -treated polyisobutylene A reaction product of aluminum amylate with P 5 where R and R are each derived from a molecule of polyisobutylene (1100 molecular weight) was prepared *7 in the following manner: 100 grams of polyisobutylene (M.W. 1100 Staudinger) were heated with 10 grams of P 5 at 425 F. for hours in a stream of nitrogen. This material was cooled to 350 F. and 110 grams of a solvent extracted parafiinic mineral oil distillate added. The product was filtered. The product contained 1.14% phosphorus and 2.35% sulfur. Then 100 grams of the oil solution of the P S -treated polyisobutylene were mixed with 37.4 ml. of aluminum amylate in kerosene (7 g. Al O /100 ml.). The mixture was heated to 300 F. for 3 hours. Nitrogen was blown through the mixture during this period to strip out the by-product amyl alcohol and kerosene. The material was filtered to give a clear product (product A). Product A bad the following elemental analysis:

Element: Wt. percent Phosphorus 0.9 Sulfur 2.1 Oxygen 0.9 Aluminum 0.8

Example II.Evaluation of product A in Caterpillar 1A Test A lubricating oil composition was then prepared which consisted essentially of 6 weight percent of product A (described in Example I) and 94 weight percent of a mineral lubricating oil (hereinafter termed base oil). The base oil was approximately 75% of a solvent extracted neutral mineral oil and of a solvent extracted mineral oil bright stock (both of Mid-Continent origin). This oil corresponded to an S.A.E. grade product and had an SSU viscosity at 210 F. of about 65 and a viscosity index of about 102. This lubricating oil composition, containing 6 weight percent of product A, was then evaluated in an engine made by the Caterpillar Tractor Co. (single cylinder Caterpillar 1A diesel test engine). The test was carried on for 120 hours using the Caterpillar lA Test Procedure CRC-L-l-545, using a 1% sulfur fuel. After running, the engine was inspected and the deposits determined. For purposes of comparison, the base oil was also evaluated in the Caterpillar 1A Test.

The following results were found in the Caterpillar 1A Test:

Demerit Ratings 1 Base Oil-{- 6 wl:., percent of Product A Base Oil Owen 1 Numerical scale in which a V'llUG of 0 denotes a perfectly clean condition and a value of 10 denotes the poorest possible condition. it will be noted that a marked improvement in engine performance was effected when using product A (oil solution of the reaction product of aluminum amylate and P s -treated polyisobutylene) as compared to the use of the base oil alone. The results in the Caterpillar 1A Test (employing 6 wt. percent of product A) were found to be comparable to the results obtained in this test when using about 9 weight percent of an outstanding commercial detergent-inhibitor additive concentrate '(containing about weight active ingredient) in the same base oil.

What is claimed is:

1. As a product, an oxygen-containing reaction product obtained by reacting about one mole of an aluminum alcoholate having the formula where R' is an aliphatic hydrocarbon group containing 1 to'20 carbon atoms with about 1 to 2 moles of a phosphosulfurized olefinic hydrocarbon at a temp rature between about to 450 F. fora period of time between about 0.2 to 10 hours with the removal of alcohol.

2. As a product, an oxygen-containing reaction prodduct obtained by reacting about one mole of an aluminum alcoholate having the formula where R is an alkyl group containing about 3 to 8 carbon atoms with about 1 to 2 moles of 21 P 8 treatedolefinic hydrocarbon at a temperature between about 200 to 35051 for a period of time between about 2 to 6 hours with the removal of alcohol.

3. Product according toclaim 2 wherein said phosphosulfurized hydrocarbon is P S -treated polyisobutylene.

4. As a product, an oxygen-containing reaction prodnot obtained by reacting about one hole of aluminum amylate with about one mole of a P S -treated polyisobutylene having a molecular weight of about 500 to 2,000 at a temperature of about 300 F. for about 4 hours, and then blowing the reaction product with nitrogen until essentially free from alcohol.

5. As a product, an oxygen-containing reaction product obtained by reacting one molar proportion of an aluminrm alcoholate having the formula AKOR');

' 6. The method which comprises reacting about 1 molar proportion of an aluminum alcoholate having the formula Al(OR) where R is an alkyl radical containing 3 to 8 carbon atoms.

10 A method for preparing a product useful as a lubricating oil additive which comprises reacting about one mole ofaluminum amylate with about one mole of a P S -treated'polyisobutylene having a molecular weight of about 500t o 2,000 at a temperature of about 300 F. for about 4 hours, and then blowing the reaction prodnot with nitrogen until essentially free from alcohol.

References Cited in. the file of this patent UNITED STATES PATENTS 2,274,302 Mulit Feb. 24, 1942 2,422,585 Rogers June 17, 1947 2,427,272 Fuller Sept. 9, 1947 2,506,570 Andress May 9, 1950 2,613,205 Hill Oct. 7, 1952 2,688,0l3 Hersh Aug. 31, 1954 2,724,725 Craig et a1 Nov. 22, 1955 

1. AS A PRODUCT, AN OXYGEN-CONTAINING REACTION PRODUCT OBTAINED BY REACTING ABOUT ONE MOLE OF AN ALUMINUM ALCOHOLATE HAVING THE FORMULA 